1. Field of the Invention
The invention relates to a colorant-containing curable composition containing a dye favorable for forming a color filter for use in liquid crystal display devices and solid-state imaging devices, a dye-containing color filter, and a production method thereof.
2. Description of the Related Art
Dyeing, printing, electrodeposition and pigment dispersion methods have been known as the methods of producing a color filter for use in liquid crystal display devices (LCDs) and solid-state imaging devices (CCD, CMOS, and the like).
Among them, the pigment dispersion method is a method of producing a color filter by photolithography by using radiation ray-sensitive colored compositions containing a pigment dispersed in various photosensitive compositions, and has an advantage that the resulting products are resistant to light, heat, and others, because they contain a pigment. Because photolithographic patterning is higher in positional precision, the method has been employed widely as a method favorable for producing color filters for large-screen, high-definition color displays.
In the pigment dispersion method, a color filter is prepared by forming colored pixels in a desirable number of color tones, by forming a coated film by coating and drying a radiation ray-sensitive composition on a glass substrate, for example, by a spin coater or a roll coater, exposing the coated film through a pattern to light, and developing the film, and additionally, repeating the operation for respective colors. Negative-type photosensitive compositions containing an alkali-soluble resin, a photopolymerizable monomer, and a photopolymerization initiator are known as the compositions for use in the pigment dispersion method (e.g., Japanese Patent Application Laid-Open (JP-A) Nos. 2-199403, 4-76062, 5-273411, 6-184482, and 7-140654).
On the other hand, recently, there exists a need for further improvement in definition of the color filters for solid-state imaging devices. However, it is difficult to improve the definition further with conventional pigment dispersion systems, and, because of the problem of unevenness in color caused by bulky pigment particles, the systems are not suited for applications that demand fine patterning, such as solid-state imaging devices,
Considering these problems, a system containing a solvent- or water-soluble dye instead of pigment is disclosed (e.g., JP-A No. 2002-278056).
However, such dye-containing curable compositions have the following new problems (1) to (4) and demand further improvement:
(1) Normally, it is difficult to obtain a liquid curable composition having a desirable spectrum, because the dye is less soluble in aqueous alkaline solutions and organic solvents.
(2) It is difficult to control the solubility (developing property) of hardened and unhardened areas, because the dye often interacts with other components in the curable composition.
(3) It is necessary to add a dye in a greater amount when the dye has a low molar absorption coefficient (ε), and thus, to relatively reduce the amounts of the polymerizable compound (monomer), binder, and other components such as photopolymerization initiator in the curable composition, resulting in problems of deterioration of the hardening property of the composition and the heat resistance and developing property after hardening.
(4) Dyes are generally lower in light resistance and heat resistance than pigments.
In addition, different front the color filters for production of semiconductors, the color filters for solid-state imaging devices demand a film thickness of 1.5 μm or less, and thus, it is necessary to add a colorant in a greater amount in the curable composition, which raises the similar problems.
Accordingly, in production of high-definition color filters, it was difficult to satisfy the practical requirements for fine thin-film colored patterns. Thus, there exists a need for development of a dye and a curable composition that solve the problems above.